Need help with custom intake!

[Racing Geek]

That actually looks really nice. I've seen a lot of "conversions" in these old Honda twins, but not too many with a wicked swingarm like that.

I have no doubt you can brace the frame. I have no doubt of your overall skills to pull this project off. And I certainly meant no disrespect. It just seems to me that it would be easier to fit the Honda tank and bodywork to your Suzuki frame than to adapt the frame to to that engine. Don't forget to upgrade triple trees!

Those high pipes could be valuable. Hard to find.

Good luck with your project.

I actually don't have the rest of the Suzuki bike. I got a deal on the engine, exhaust, carbs, and wiring so I got it to try the swap.
The entire front end is CBR600 F2. The F2 uses the exact same bearings as the CL360 too so it was literally a bolt on upgrade. The clipons are from a VTR1000.

I've actually got two sets of the high pipes with heat shields. I'm trying to sell one to fund the swap and I'm going to try selling the other with the complete CL360 engine (engine, carbs, exhaust, wiring) when I get the GS engine running.


This is the geometry of the bike and some of the specs...

54.75" wheel base (center of adjustment)
25* rake
4.5" trail
4.25" front suspension travel
3" rear suspension travel
7.5" ground clearance
31.5" seat height
350# estimated wet weight (I was at 300# wet with the stock motor)
~80hp?




As for keeping you guys updated... I have a build thread on customfighters.com that I have been updating periodically. I also started on dotheton.com but kept forgetting about it since I don't go on there often. I'll probably be around here more since I'll probably be reading a bunch about the GS engines but I don't know if I want to keep two build threads going at once.

[koolaid_kid]

Lets face it, the Honda twins were nothing to write home about, performance-wise. But they were relatively reliable, considering.
Those pipes like pretty standard CL pipes, but nice.
I really like the swingarm, looks tough and durable.
The siamesed carbs I spoke of were two carbs joined together, perhaps they were more compact? IIRC they came on certain 550 Suzis, but I am sure other Japanese bikes had them as well.
AFA going with 2 instead of 4 carbs, it would be similar to the old carbureted 4s, 6s and V8s before fuel injection took over the automotive world. We are so immersed in the "one carb, one cylinder" thought pattern that we forget the 50s and 60s in-line 6s had a one barrel carburetor, possibly a two barrel. Even the V8s had a two barrel unless you bought the performance version.
You need to work backwards to calculate what you need if you go with two instead of four. Since the engine is basically an air pump, how much air do you expect to pump at full RPM? You know the volume of the engine (~750cc), you know the RPM you expect to reach, you can calculate the flow. Work backward to see if the carbs selected can match that. Then you can tune the lower ranges, knowing that you will lose a bit of low end grunt by using the dual rather than the quad approach.

[BassCliff]

"Siamese carbs"

Hi,

Not sure what you mean by "Siamesed carbs."

For a visual, see the parts fiche picture for an '84 GS550. A "siamese carb" has two throats and one slide.




Thank you for your indulgence,

BassCliff

[AJ]

My '69 CB350 could pop wheelies in 3rd gear, but top speed was not too great. Those motors could take a lot of compression without throwing bottom ends. Really durable little beasties for their day. Needle bearing cam caps and megacycle cams. And nowadays the vintage racers have added all sorts of upgrades.

Thinking about your carb challenge.... look at the intake manifold to a Harley Sportster 883. You might be able to use two of those and some plumbing to make a nice, smooth 1 carb into 2 jugs setup. The older ones were rubber (Gen1 Evo), not sure about the newer ones. Then all you need is a pipe with a small bend to go from the manifold to each of the intake rubbers on the Zuk motor.

[Racing Geek]

I do have an S&S Harley manifold to try but just by looking at it the angle will be way too wide. It will end up being really short (carb will stay close to the motor) which is good but the bends are going to be really sharp and hurt flow. I'm planning to use 3/16" plate for the flanges that bolt to the head and some 1.25" exhaust tube to make the intake runners. I'll probably end up rolling some sheet metal to match the OD of the carbs head side and then using a hose to attach the carb to the manifold. Since that hose will be flexible I plan to have a bracket come down from the frame help support the carbs.

[AJ]

I do have an S&S Harley manifold to try but just by looking at it the angle will be way too wide. It will end up being really short (carb will stay close to the motor) which is good but the bends are going to be really sharp and hurt flow. I'm planning to use 3/16" plate for the flanges that bolt to the head and some 1.25" exhaust tube to make the intake runners. I'll probably end up rolling some sheet metal to match the OD of the carbs head side and then using a hose to attach the carb to the manifold. Since that hose will be flexible I plan to have a bracket come down from the frame help support the carbs.

Hmmm, wonder what the spacer was like on the Triumph 650 Tiger. The bends in that manifold are truly horrible.
http://www.britbike.com/forums/ubbth...&Number=146741

How about getting a good exhaust shop to make you two nice S-offset pipes in stainless. Slice off the sides after the bend in both pipes, weld the open cuts together, re-form it into a circle, maybe re-weld it since you'll probably damage the welds. You don't have a lot of length to play with here.

[Wyldesoul]

Sums it up for me.

Kind of a DIY crackpot idea to put a way too powerful engine in there.

Don't anybody have any respect for all the testing and work hours the factory engineers put into a bike?

Take it for granted they already been there, and it didn't work.

Well I must say that is a horridly pessimistic way to look at modifications.

I mean, especially such wild, radical and downright awesomely idiotic things!
Where is your hot rod spirit? Weren't the original "hot rods" just small, entry level cars with way to big and way to powerful motors shoehorned in with no regard to safety or structural stability?

If it weren't for those crackpot DIY guys, the car industry would never have recognized such a demand, and would never have sent their teams of engineers to figure out how they can make something like that to sell, and we'd never have muscle cars.

Even the motorcycle industry has taken tips from crackpot DIY guys. If enough people do it, they see that it's liked, and they find a way to make it themselves. But if everyone just trusted the engineers knew what they were doing, and leave things alone, the motor industry would be much, much blander than it is now.


My input to the project that is the subject of this thread?
Go for it! You are without a doubt being some shade of idiot for trying this, and if you kill yourself it is your own **** fault.
But if you succeed?

Sweeeeeet. That will be one killer ride.

[boontonmike]

I'm all about modifying stuff out the ass, but that frame is just about the last style frame I would want to use for a big 4 cyl. If anything I'd be trying to stick a super light dr650 / 400 or some thumper thats built up and weighs next to nothing and would fit the frame alot better. To be fair though it is your project and if you really are into it go for it, I'm not gunna stop ya.

[AJ]

I'm all about modifying stuff out the ass, but that frame is just about the last style frame I would want to use for a big 4 cyl. If anything I'd be trying to stick a super light dr650 / 400 or some thumper thats built up and weighs next to nothing and would fit the frame alot better. To be fair though it is your project and if you really are into it go for it, I'm not gunna stop ya.

That actually makes some sense.

You could also hotrod the heck out of the original motor.

But there is that "impossible dream" thing to be considered.

[Steve]

For a visual, see the parts fiche picture for an '84 GS550. A "siamese carb" has two throats and one slide.




Thank you for your indulgence,

BassCliff

For a little more "fun", here is a visualization from the only other bike that I know of with siamesed carbs, the KZ1300 from '79 to '82.



You think it's bad with two of those suckers? Try it with THREE of them.
.

[Racing Geek]

Hmmm, wonder what the spacer was like on the Triumph 650 Tiger. The bends in that manifold are truly horrible.

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=146741

How about getting a good exhaust shop to make you two nice S-offset pipes in stainless. Slice off the sides after the bend in both pipes, weld the open cuts together, re-form it into a circle, maybe re-weld it since you'll probably damage the welds. You don't have a lot of length to play with here.

That link isn't working for me.
I don't remember the exact measurement but I think it was 5" to 6" of room to make the manifolds. I've actually been considering making the intake out of foam and casting them from aluminum like the manifolds for the CB750.

Well I must say that is a horridly pessimistic way to look at modifications.

I mean, especially such wild, radical and downright awesomely idiotic things!
Where is your hot rod spirit? Weren't the original "hot rods" just small, entry level cars with way to big and way to powerful motors shoehorned in with no regard to safety or structural stability?

If it weren't for those crackpot DIY guys, the car industry would never have recognized such a demand, and would never have sent their teams of engineers to figure out how they can make something like that to sell, and we'd never have muscle cars.

Even the motorcycle industry has taken tips from crackpot DIY guys. If enough people do it, they see that it's liked, and they find a way to make it themselves. But if everyone just trusted the engineers knew what they were doing, and leave things alone, the motor industry would be much, much blander than it is now.


My input to the project that is the subject of this thread?
Go for it! You are without a doubt being some shade of idiot for trying this, and if you kill yourself it is your own **** fault.
But if you succeed?

Sweeeeeet. That will be one killer ride.

Not sure what to make of everyones talk of "idiot." If it makes you all sleep better at night, I do have a background in mechanical engineering and this isn't my first project.

I'm all about modifying stuff out the ass, but that frame is just about the last style frame I would want to use for a big 4 cyl. If anything I'd be trying to stick a super light dr650 / 400 or some thumper thats built up and weighs next to nothing and would fit the frame alot better. To be fair though it is your project and if you really are into it go for it, I'm not gunna stop ya.

If I wanted a supermoto I would simply ride my KTM instead of doing this. I'm curious why everyone thinks this frame is such a bad choice. Is it because it is physically small compared to the frame the engine came out of? Is it because I cut away so much of the back bone? Please share.

I'm not trying to be smart ass. I just figured if people have an issue with what I'm doing it would be good to discuss it (in a civilized manner) since someone may have something to say that has slipped my mind.

That actually makes some sense.

You could also hotrod the heck out of the original motor.

But there is that "impossible dream" thing to be considered.

That is pretty much why I'm doing this. How many people would ever consider this? Now how many of those people would actually follow through with the idea? I'm hoping this will be a true one of a kind bike when I'm done. For those of you in the midwest part of the United States, I'm hoping to have the bike in the show at Rockerbox in Milwaukee and do the Fall Slimey Crud Run on it this year. I'll probably end up doing the Spring Crud Run on the KTM or Triumph. If any of you will be doing it let me know and maybe we can ride together for part of it.

For a little more "fun", here is a visualization from the only other bike that I know of with siamesed carbs, the KZ1300 from '79 to '82.

You think it's bad with two of those suckers? Try it with THREE of them.
.

I know a guy with a KZ1300. Those things are tanks and the 6-1 exhaust makes the thing sound like an exotic car. Sex for the ears.

I would imagine it's probably just as bad as cleaning and synching all 6 CBX carbs. This bike I'm building is sort of my way of getting the CBX back (motor went boom and it was sold). It will have similar looks, a better power to weight ratio, and probably just as much of a "wow" factor all for under a grand.


I'm going to a swap meet Sunday so hopefully I'll find some carbs there. If not I know of a pair of VM34's for a nice price. I've decided I don't want to use CV's on the bike if I can get away with it.

[Steve]

I would imagine it's probably just as bad as cleaning and synching all 6 CBX carbs.

Actually, it was rather easy to sync them.

Only three carbs, TWO adjustments, you're done.
Of course, I did have to spend a few more bucks and get the SIX-tube set of mercury sticks.
Still have them, still use them.

.

[koolaid_kid]

And it really does not matter whether you agree or not. I personally would not stuff a 1000 hp motor in a standard car frame, but some do.
We are here to assist, not to judge.
At least, that is my take on it.

[boontonmike]

I think the outcry over the frame is because the frame is only a single tube downtube and toptube. Atleast thats why I don't like it. The engine has alot of torque and without the support of a dual downtube and alot more supports like most bigger japanese 4 cyl frames (which alot of people even complain about and brace up) its's going to want to flex alot. It will without a doubt work physically.

I think the sheer massiveness of the engine and how wide it is on such a small chassis design just doesn't flow. I think the original engine and exhaust configuration looked perfect. Now again this is all just one opinion, take it with a grain of salt, and do whatever you please as everyone should.



What kind of KTM do you have? I wanted a 525 and ended up getting a DRZ400E with a street title. Still dream about the KTMs though.

[Wyldesoul]

Not sure what to make of everyones talk of "idiot." If it makes you all sleep better at night, I do have a background in mechanical engineering and this isn't my first project.

There is the fact of a very large motor in a very small frame is just inherintly dangerous, but in a seriously awesome way.

Just like motorcycling itself. We all have to be some shade of idiot to get out on what is functionally an engine with wheels, blasting down the highway at seventy miles per hour with nothing between us and the world to keep us safe.

But the joy of the experience is well worth the risk, and so it's okay that we're all a bit of an idiot for being in this hobby.

I didn't mean it insultingly, more in the way that they call some truly radical hot rods "Daft" or "looney" or "crazy" and so forth.